The Central Neurochemistry Service functions as a centralized laboratory for analysis of neurotransmitters and metabolites in body fluids collected within the intramural program. Routine analyses include norepinephrine in plasma, urine and CSF, epinephrine in urine and plasma, dopamine and dopamine sulfate in urine, plasma and CSF, catecholamine metabolites, HVA, MHPG and DOPAC in CSF, plasma and urine, serotonin in platelets and platelet poor plasma and 5HIAA in plasma, CSF and urine. GC-MS assays are used for total urinary norepinephrine, epinephrine and dopamine and urinary VMA, MHPG and normetanephrine. HPLC with electrochemical detection is used for other analyses. Modifications of existing procedures allow simultaneous determination of HVA, 5HIAA and MHPG in plasma. This allows simultaneous observation of drug and/or diurnal effects on metabolites of three different neurotransmitter systems. Over 8500 assays were performed on over 6000 samples which were processed.